Coal cutting bit having three cutting tips



Fb. 17, 1959- I M, F 2,873,960

" COAL CUTTING-BIT HAVING THREE CUTTING TIPS Filed Nov. 15, 1957 INVENTOR. '2" MARVIN Y -THRNE AT ORN NS United COAL CUTTING BIT HAVING THREE CUTTING TIPS This invention relates to cutting bits, and more particularly to a coal cutting bit of the type having carbide inserts in the cutting points thereof.

A main object of the invention is to provide a novel and improved coal cutting bit which is simple in construction, which is arranged so that wear on the points thereof occurs substantially uniformly, and which is especially suitable for use in coal cutting machines.

A further object of the invention is to provide an improved coal cutting bit which is relatively inexpensive to fabricate, which is arranged so that the points thereof are protected against breakage, and which may be kept in operation for a long period of time, as compared with previously known coal cutting bits.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

Figure l is a side elevational view of a miners bit constructed in accordance with the present invention.

Figure 2 is a front elevational view of the miner's bit of Figure 1.

Figure 3 is a rear elevational view of the miners bit of Figure 1.

Figure 4 is a top plan view of the miners bit shown in Figures 1, 2 and 3.

Referring to the drawings, 11 generally designates an improved miners bit, especially suitable for coal mining, according to the present invention.

The bit 11 comprises a straight shank 12 which is of rectangular transverse cross section, and which is formed with an enlarged head 13. The head 13 is formed with substantially triangular spaced points 14, 15 and 16, said points being provided with suitable carbide tips 17 or tips of any other suitable hard, wear-resistant material As shown in Figure 1, the intermediate point 16 is offset inwardly and upwardly, as compared with the forward points 14 and 15. The forward points 14 and 15 have a fiat, common side face 16' which extends substantially parallel to and is laterally ofiset from the shank 12, the face 16 being formed at its top end with the V-notch 17, defining the triangular points 14 and 15, above mentioned. The point 16 has a flat forward face 18' which is parallel to the face 16 but which is ofiset rearwardly therefrom, as is clearly shown in Figure 1. As is readily apparent from Figures 2, 3 and 4, the intermediate point 16 is located in a vertical longitudinal plane extending centrally through the bit, and the points 14 and 15 are symmetrically located on opposite sides of said plane.

As will be evidenced from Figures 2 and 3, the head portion 13 flares upwardly in width from its connection to the top end of the shank 12. The head is formed on its top surface with the external, upwardly facing V-grooves 18 and 19, defining the points therebetween, said grooves extending downwardly and away from said points, defining V-shaped, upwardly convergent ribs 20, 21 and 22, leading to the points 15, 16, and 14, respectates Patent 2 tively. As will be further apparent from Figure 1, the ribs are arcuately curved downwardly and away from said points.

In using the bit, the points engage the material being out, such as high sulphur coal, or the like, the cutting action being derived by the cooperation of side points 14 and 15 with the center point 16 as the bit engages the material. When the center bit point 16 wears down, the side points 14 and 15 continue their cutting action, whereby the bit may be kept in operation over a long period of time without requiring replacement.

As will be readily apparent, when the cutting edges wear down, the edges may be easily resharpened by means of a suitable grinding implement shaped to engage in the grooves 19 and 18, or the worn bit may be merely discarded and replaced by a new bit.

The cutting bit above described is especially useful in coal mining machines employing chains to carry the bits and supporting the bits for cutting engagement with the coal or other material being penetrated.

As previously mentioned, the head 13 flares upwardly in width from its connection-to the top end of the shank 12. As will be further apparent from Figure 4, the head 13 flares horizontally in width toward the side points 14 and 15, whereby the rearward edges of the ribs 14, 15 and 16 are relatively close together and the distance between said edges increases toward the points 16, 14 and 15.

While .a specific embodiment of an improved coal miners bit has been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

l. A miners bit of the character described comprising a straight shank and an enlarged head on the end of shank, said head having a flat front face extending substantially parallel to said shank and being formed with a V-notch at its top end, defining a pair of points at said front face, and a third point formed on said head midway between and spaced rearwardly and upwardly from said pair of points, said third point having a flat triangular front face parallel to said shank, said head being formed with external V-grooves between said points extending downwardly and rearwardly from said points, defining V-shaped ribs on the head leading to said points.

2. A miners bit of the character described comprising a straight shank and an enlarged head on the end of said said shank, said head having a flat front face extending substantially parallel to said shank and being formed with a V-notch at its top end, defining a pair of points and a third point formed in said head midway between and spaced rearwardly and upwardly from said pair of points, said third point having a flat triangular front face parallel to said shank, said head being formed with external V-grooves between said points extending downwardly and rearwardly from said points, defining V-shaped ribs on the bead leading to said points, said ribs being arcuately curved downwardly and rearwardly from said points.

References Cited in the file of this patent UNITED STATES PATENTS 1,841,268 McKinlay Jan. 12, 1932 2,395,545 Genter Feb. 26, 1946 FOREIGN PATENTS 155,251 Australia Feb. 12, 1954 

